Assessment versions

Published (reviewed and quality assured)

Rationale

Justification for indicator selection

Since water temperature is mainly determined by heat exchange with the atmosphere, higher air temperatures lead to higher water temperatures. Higher water temperatures, particularly in standing waters and low-flow situations in rivers, will bring about changes in the physico-chemical condition of water bodies with subsequent impacts on biological conditions. This may have severe consequences for ecosystem structure and function as well as for water use and ecosystem services.

Impacts of increased water temperatures may also include more stable vertical stratification of deep lakes and increased oxygen depletion in lake bottoms (stratification in other lakes may become less stable), more frequent harmful algal blooms, reduced habitats for cold-water aquatic species, and increased incidence of temperature-dependent diseases.

Human intervention can only help freshwater ecosystems to adapt to increasing water temperature in a limited way, for example by reducing the pressures from other human activities such as pollution by nutrients and hazardous substances and pressure from hydromorphological modifications. Such actions may make the water bodies less vulnerable to stress resulting from higher water temperature. Additional pollution load reduction measures may be needed in river basin management plans to obtain good ecological status, as required by the Water Framework Directive.

Indicator definition

Water temperatures in five selected European rivers and lakes in the 20th century

Units

degrees centigrade (⁰C)

Policy context and targets

Context description

Water temperature of rivers and lakes is one of the central parameters that determine the overall health of aquatic ecosystems because aquatic organisms have a specific range of temperatures that they can tolerate.

Preparing for climate change is a major challenge for water management in Europe. Climate change is not explicitly included in the text of the Water Framework Directive. However, water management under the WFD will have to deal with the challenges posed by climate change (EEA, 2007). The stepwise and cyclical approach of the WFD River Basin Management Plans (RBMPs) process makes it well suited to adaptively manage climate change impacts. In particular, the review of RBMPs every six years establishes a mechanism to prepare for and adapt to climate change.

Targets

No targets have been specified.

Related policy documents

Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives in the future. This web portal provides information on all adaptation activities of the European Commission.

In April 2013, the European Commission adopted an EU strategy on adaptation to climate change, which has been welcomed by the EU Member States. The strategy aims to make Europe more climate-resilient. By taking a coherent approach and providing for improved coordination, it enhances the preparedness and capacity of all governance levels to respond to the impacts of climate change.

Methodology

Methodology for indicator calculation

Annual average water temperature in River Rhine and River Meuse (1911–2010); River Danube (1901–1998), Lake Võrtsjärv (1947–2011), and average water temperature in August in Lake Saimaa, Finland (1924–2011) are displayed.

Trend lines have been added.

Methodology for gap filling

Not applicable

Methodology references

No methodology references available.

Data specifications

EEA data references

No datasets have been specified here.

Data sources in latest figures

Uncertainties

Methodology uncertainty

Not applicable

Data sets uncertainty

The attribution of water temperature increase to climate change is difficult as other effects like increased use of cooling water take place at the same time.